IEC 61850 RTU Firmware Development

I am building a new Remote Terminal Unit and need production-ready firmware that covers three core areas: protection and control logic, full monitoring and metering capability, and the communication layer that ties everything together. The finished image must speak Modbus, DNP3, and IEC 61850 natively so it can slot straight into modern substation or plant networks without external gateways. Alongside protocol compliance I expect secure boot, robust fault handling, and efficient memory use typical of an embedded C/C++ codebase; if you prefer another language or an RTOS approach, show me why it will meet the same reliability bar. Deliverables • Compilable source code and build scripts • Protocol conformance test reports for Modbus, DNP3, IEC 61850 • A brief user manual covering configuration registers, memory map, and firmware update procedure • Support during bench testing until the RTU passes factory acceptance If you have a previous IEC 61850 or utility-grade firmware project in your portfolio, that will help me gauge fit. Let me know the development environment you plan to use and any third-party stacks you would integrate so I can clear licensing early.